1. Field of the Invention
The present invention relates to a rolling mill for rolling a steel strip or a steel bar. More specifically, the invention relates to a rolling mill in which both ends of upper and lower work rolls are supported by upper and lower bearing blocks, respectively, and these upper and lower work rolls are pulled to each other vertically to screw down the upper work roll, thus obviating the need for housings.
2. Description of the Related Art
Among conventional rolling mills, there is a rolling mill as shown in FIGS. 11 and 12. In these drawings, the reference numeral 51 designates an upper work roll, and 52 a lower work roll. These work rolls are rotatably mounted, by their shafts, to upper roll chocks 53 and lower roll chocks 54, and are mounted internally above and below a pass line of housings 61. The reference numeral 55 designates a screw, and 56 a screw-down cylinder for finely adjusting the height of the upper work roll 51. The reference numeral 57 designates an upper cross cylinder, and 58 a lower cross cylinder. To the front ends of rod portions of these cross cylinders, crossheads 59, 60 are mounted for engagement with the upper roll chock 53 and the lower roll chock 54.
In the housing 61 on a work side, upper thrust point blocks 62 and lower thrust point blocks 72 are mounted. Into the upper roll chock 53, as shown in FIG. 11, a four-link type thrust point device is inserted by use of the upper thrust point blocks 62. The thrust point device is composed of rollers 63 fitted into notched portions 62a of the thrust point blocks 62, shafts 65 supporting the rollers 63 and levers 64, the shafts 65 and the levers 64 being pivotably attached to the upper roll chock 53, and a link 66 connecting both levers 64 together. Into the lower roll chock 54, too, a similar four-link type thrust point device is inserted by use of the lower thrust point blocks 72.
The screw 55 is turned to adjust the heights of the upper roll chock 53 and the upper work roll 51, and set the roll gap between the upper work roll 51 and the lower work roll 52 necessary for the rolling of a strip material 50. The upper and lower cross cylinders 57, 58 are actuated to turn the upper work roll 51 and the lower work roll 52 in the opposite directions about a cross point, C.sub.P, causing them to cross at a required cross angle, .theta.. The upper work roll 51 and the lower work roll 52 are rotationally driven by a drive device (not shown) to bring the strip material 50, which has been conveyed, into engagement with them. The height of the upper work roll 51 is finely adjusted by the screw-down cylinder 56. Also, the cross angle .theta. is finely adjusted by the upper and lower cross cylinders 57, 58. Under these actions, the strip material 50 is rolled with its thickness and shape being kept satisfactory, to have a desired thickness.
The foregoing conventional rolling mill needs the heady housings 61 incorporating the upper and lower roll chocks 53, 54, a screw-down device of a complicated structure having the screw 55 and the screw-down cylinder 56, and the four-link type thrust point device of a complicated structure. Thus, the manufacturing cost and the maintenance cost for the rolling mill are high, and a wide installation space is required. Furthermore, the width of the housing in the direction of rolling is so large that rolling mills of this type, if arranged tandem in a row, create a long line.